Spectral Reflectance of Sintered Oxides

Spectral reflectance in the 0.23 to 2.65μ region was measured on sintered oxides of Al₂O₃, CeO₂, TiO₂, Y₂O₃, and ZnO. The oxides were sintered at various temperatures up to 1550°C. Large changes in reflectance occurred as a result of different extents of sintering of the specimens. The data were interpreted in terms of changes in the distance between the particles, the water content, and the surface roughness. Loss of trace-water and decrease in surface roughness result in an increase in reflectance, whereas shrinkage of the specimen causes a decrease in reflectance.